Cutting segment for cutting tool and cutting tools

ABSTRACT

The invention provides a cutting segment for a cutting tool for cutting or drilling a brittle work piece such as stone, bricks, concrete and asphalt, and a cutting tool having the cutting segment. The cutting segment includes a cutting surface for cutting a work piece and a plurality of abrasive particle layers. The abrasive particle layers are disposed perpendicular to a cutting direction. Each of the abrasive layers has a plurality of abrasive particle rows in a width direction of the cutting segment. Each of the abrasive rows has a plurality of abrasive particles arranged in a line. Further, the abrasive layers have a plurality of blank sections therebetween. In the blanks sections, abrasive particles are absent or have a concentration of 70% or less with respect to those in the abrasive rows. In addition, the blank sections include relatively thick blank sections and relatively thin blank sections.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage application of InternationalApplication No. PCT/KR2006/001442, with an international filing date ofApr. 19, 2006 based on Korean Patent Application No. 2005-33340 filed onApr. 21, 2005 and Korean Patent Application No. 2006-21939 filed on Mar.8, 2006.

TECHNICAL FIELD

The present invention relates to a cutting segment for a cutting toolfor cutting or drilling a brittle work piece such as stone, bricks,concrete and asphalt, and a cutting tool having the cutting segment.More particularly, the present invention relates to a cutting segmentimproved in cutting rate and useful life by properly arranging abrasiveparticles, and a cutting tool having the cutting segment.

BACKGROUND ART

To cut or drill a brittle work piece such as stone, bricks, concrete andasphalt requires abrasive particles having higher hardness than a workpiece.

The abrasive particles are exemplified by artificial diamond particles,natural diamond particles, nitrogen boride and super-hardness particles,of which artificial diamond particles are most widely used.

An artificial diamond (hereinafter referred to as “diamond” was inventedin the 1950s. The diamond, which is known to have the highest hardnessout of materials in the earth, has been accordingly used for cutting andgrinding tools due to such properties.

Especially, the diamond has been broadly used in a stone processingfield where stone such as granite and marble is cut and ground, and in aconstruction field where a concrete structure is cut and ground.

A cutting segment and a cutting tool, which will be explained hereunder,employ diamond particles as abrasive particles.

Typically, a diamond tool comprises segments having diamond particlesdispersed therein and a metal core having the segments fixed thereto.

FIG. 1 illustrates an example of a segment type diamond tool.

As shown in FIG. 1, the segment type diamond tool 1 includes a pluralityof segments 11 and 12 fixed to a disk-shaped metal core 2, in which eachof the segments 11 and 12 has diamond particles 5 randomly dispersedtherein.

The segments are fabricated via powder metallurgy in which the segmentsare mixed with metal powder, molded and then sintered.

In case of mixing the diamond particles with the metal powder as justdescribed, the diamond particles are not evenly dispersed among themetal powder but randomly dispersed inside the cutting segment.

In the cutting tool having the cutting segment, its cutting rate iscontradictory to its useful life.

For example, in case of using the metal powder with low abrasionresistance to enhance cutting rate, useful life of the cutting segmentis shortened. In contrast, in case of using the metal powder with highabrasion resistance to extend useful life, the diamond particles bluntedduring cutting do not easily fall off, thus lowering cutting rate.

In addition, in case of mixing the diamond particles with the metalpowder serving as a bond as just described, the diamond particles arenot uniformly dispersed owing to differences between metal powders anddiamond particles in terms of particle size and specific gravities.Therefore, as shown in FIG. 1, this disadvantageously leads to a cuttingsurface 3 having too many diamond particles or a cutting surface 4having too few diamond particles, causing the diamond particles tosegregate.

To overcome such problems, a cutting segment having diamond particlesuniformly arranged has been suggested as shown in FIG. 2.

FIG. 2 (b) is a cross-sectional view of a cutting segment taken alongthe line A-A in FIG. 2( a), when used during a cutting process.

As shown in FIG. 2 (a), the cutting segment 20 has diamond particles 25arranged in rows 21 in a cutting direction (in a length direction of thecutting segment). The diamond rows 21 are disposed in a width directionof the cutting segment to form a plurality of diamond particle layers 31as shown in FIG. 2( b). The diamond layers are stacked in a thicknessdirection of the cutting segment.

As shown in FIG. 2 (b), the diamond particle layers 31 of the diamondparticle rows 21 having the diamond particles 25 arranged are uniformlyspaced apart from each other. In case of using the diamond particlessmaller than a gap D between the diamond particle layers, the diamondlayers 31 have an area without the diamond particles 41 therebetween.

In cutting a work piece via the cutting segment 20, blank sections areworn away first, thus generating grooves. The depth h of the groovesincreases in proportion to the gap D between the diamond particle rows.If the depth h of the grooves of the blank sections is ⅔ of the averagediameter of the abrasive particles, the diamond particles 25 easily falloff due to decline in retention by the metal powder.

Meanwhile, a small depth of the grooves improves useful life of thecutting segment but diminishes cutting rate owing to low protrusion ofthe abrasive particles.

In this fashion, the cutting segment 20 prevents the diamond particles25 from segregating, thereby maximizing work efficiency for the diamondparticles 25. Also, cutting rate can be boosted through a specialconcept of a “shoveling effect.” However, due to the diamond particlerows equally spaced apart from each other, with increase in the depth hof the groove, the metal powder cannot sufficiently retain the diamondparticles 25 so that the diamond particles are easily discharged duringcutting.

In the end, the diamond particles 25 fall off not by abrasion but by alacking retention power despite their cutting capability. Thisdisadvantageously reduces useful life, especially for a work piece cutinto large debris.

DISCLOSURE OF INVENTION Technical Problem

The present invention has been made to solve the foregoing problems ofthe prior art and therefore an object according to certain embodimentsof the present invention is to provide a cutting segment improved incutting rate and useful life by adjusting the thickness of a blanksection with no abrasive particles, and a cutting tool having thecutting segment.

Technical Solution

The present invention will be explained hereunder.

According to an aspect of the invention for realizing the object, thereis provided a cutting segment for a cutting tool comprising a pluralityof abrasive particle layers disposed perpendicular (thickness direction)to a cutting direction, each of the abrasive layers having a pluralityof abrasive particle rows stacked in a width (vertical) direction of thecutting segment, each of the abrasive rows having a plurality ofabrasive particles arranged in a line, wherein the abrasive particlelayers have a plurality of blank sections therebetween, in whichabrasive particles are absent or have a concentration of 70% or lesswith respect to those in the abrasive rows, and wherein the blanksections include relatively thick blank sections and relatively thinblank sections (thickness in a direction perpendicular to a cuttingdirection, i.e., a gap between abrasive particles).

According to another aspect of the invention for realizing the object,there is provided a cutting segment for a cutting tool comprising aplurality of abrasive particle layers disposed perpendicular (thicknessdirection) to a cutting direction, each of the abrasive particle layershaving a plurality of abrasive particle rows stacked in a width(vertical) direction of the cutting segment, each of the abrasiveparticle rows having a plurality of abrasive particles arranged in aline, wherein the abrasive particle layers include therebetween aplurality of blank sections in which the abrasive particles are absentor have a concentration of 70% or less with respect to those in theabrasive particle rows, or a plurality of non-blank sections in whichthe abrasive particle layers contact or overlap each other.

According to further another aspect of the invention for realizing theobject, there is provided a cutting segment for a cutting toolcomprising at least two regions, each having a plurality of abrasiveparticle layers disposed perpendicular to a cutting direction in each ofthe regions, each of the abrasive particle layers having a plurality ofabrasive particle rows stacked in a width direction of the cuttingsegment, each of the abrasive particle rows having a plurality ofabrasive particles arranged in a line, wherein the abrasive particlesare absent or have a concentration of 70% or less with respect to thosein the abrasive rows, wherein the blank sections include relativelythick blank sections and relatively thin blank sections, and wherein atleast some portions of the abrasive particle layers in leading andtrailing ones of the regions are arranged so that a thin blank sectionof the trailing region passes along a thick blank section of the leadingregion during cutting of the work piece.

According to further another aspect of the invention for realizing theobject, there is provided a cutting segment for a cutting toolcomprising at least two regions, each of the regions having a pluralityof abrasive particle layers disposed perpendicular to a cuttingdirection in each of the regions, each of the abrasive particle layershaving a plurality of abrasive particle rows stacked in a widthdirection of the cutting segment, each of the abrasive particle rowshaving a plurality of abrasive particles arranged in a line, wherein theabrasive particle layers include therebetween a plurality of blanksections in which the abrasive particles are absent or have aconcentration of 70% or less with respect to those in the abrasiveparticle rows and a plurality of non-blank sections in which theabrasive particle layers contact or overlap each other, and wherein atleast some portions of the abrasive particle layers in leading andtrailing ones of the regions are arranged so that a non-blank section ofthe trailing cutting region is disposed in a blank section of theleading cutting region during cutting of a work piece.

According to further another aspect of the invention for realizing theobject, there is provided a cutting tool having the cutting segment ofthe invention as described above.

According to further another aspect of the invention for realizing theobject, there is provided a cutting tool comprising: a plurality ofcutting segments having abrasive particles dispersed therein; and ametal core having the cutting segments fixed thereto, wherein thecutting segments comprise a cutting segment of the invention asdescribed above, and wherein at least some portions of abrasive particlelayers in leading and trailing ones of the cutting segments are arrangedso that a thin blank section of the trailing cutting segment passesalong a thick blank section of the leading cutting segment duringcutting of the work piece.

According to further another aspect of the invention for realizing theobject, there is provided a cutting tool comprising: a plurality ofcutting segments having abrasive particles dispersed therein; and ametal core having the cutting segments fixed thereto, wherein thecutting segments comprise a cutting segment of the invention asdescribed above, and wherein at least some portions of abrasive particlelayers in leading and trailing ones of the cutting segments, a non-blanksection of the trailing cutting segment is disposed in a blank sectionof the leading cutting segment during cutting of a work piece.

The present invention will be explained in greater detail hereunder.

The present invention is directed to a cutting segment for a cuttingtool for cutting or drilling a brittle work piece such as stone, bricks,concrete and asphalt, and a cutting tool having the cutting segment.

The cutting segment for the cutting tool includes abrasive particles forperforming cutting on a work piece and a metal powder as a bond forfixing the abrasive particles.

The invention is directed to arrangement of the abrasive particles.

According to an exemplary cutting segment of the invention, the abrasiveparticles are arranged in rows in a cutting direction of the cuttingsegment and the abrasive rows are stacked vertically from (in a widthdirection of) the cutting segment to form a plurality of abrasivelayers. The abrasive particle layers are disposed perpendicular (in athickness direction of the cutting segment) to a cutting direction.Preferably, the number of the abrasive particle layers is four or more.

That is, each of the abrasive particle layers include a plurality ofabrasive particle rows so that the abrasive particle rows appear on acutting surface during cutting of a work piece.

The abrasive rows of the abrasive layers are evenly or unevenlyconcentrated in a length direction of the cutting segment.

That is, the abrasive rows are structured such that the abrasiveparticles may be equally spaced apart from each other (evenlyconcentrated) or at least some of the abrasive rows may be spaced apartfrom each other at different intervals (unevenly concentrated).

Also, at least two of the abrasive layers stacked in a thicknessdirection are equally concentrated.

That is, the abrasive particle layers may be concentrated evenly orunevenly. Preferably, the abrasive particle layers in a lateral portionof the cutting segment have a concentration greater than those in acentral portion of the cutting segment.

Between the abrasive particle layers are blank sections in which theabrasive particles are absent or have a concentration of 70% or lesswith respect to those in the abrasive particle rows.

The blank sections include relatively thick (in a directionperpendicular to a cutting direction, i.e., a gap between abrasiveparticles) blank sections (hereinafter “thick blank sections”) andrelatively thin blank sections (hereinafter “thin blank sections”).

According to the invention, preferably, the thin blank sections aredisposed between the thick blank sections. More preferably, the numberof the thin blank sections disposed between the thick blank sections isless than four.

The thick blank sections successively arranged weakens a power to retainthe abrasive particles owing to more abrasion of metal powder, therebycausing the cutting segment to be rapidly worn away. Meanwhile, four ormore of the thin blank sections successively arranged reduces protrusionheight of the abrasive particles due to too shallow grooves in the thinblank sections, consequently deteriorating cutting rate.

Preferably, the thick blank sections each have a thickness of 0.75 to 2times the average diameter of the abrasive particles. The thickness lessthan 0.75 times the average diameter of the abrasive particlesexcessively shallows grooves caused by abrasion, lowering protrusionheight of the abrasive particle rows and thus diminishing cutting rate.In addition, the thickness more than 2 times excessively deepens thegrooves resulting from abrasion, thereby potentially degrading usefullife and stability of the cutting segment.

Preferably, the thin blank sections each have a thickness smaller thanthe thick blank sections each in a range that the abrasive particlesarranged in two abrasive particle rows do not overlap, i.e., a rangegreater than 0.

Preferably, a thickness ratio of the thin blank sections to the thickblank sections is 1.5 times or more.

Preferably, the abrasive particle rows are stacked such that theabrasive particles are protruded successively on the cutting surfacewith uniform patterns during cutting of a work piece.

According to the invention, the blank sections each are not limited tothe one having the thin blank sections and the thick blank sections withthe same thickness, respectively. The thin blank sections may includetwo or more thin blank sections having a different thickness and alsothe thick blank sections may include two or more thick blank sectionshaving a different thickness.

Preferably, a relatively thinnest one of thick blank sections has athickness ratio of 1.5 times or more with respect to a relativelythickest one of the thin blank sections.

Further, a plurality of non-blank sections may be disposed between theabrasive particle layers of the cutting segment.

To form the non-blank sections, adjacent abrasive particle layers arearranged such that the abrasive rows of the adjacent abrasive particlelayers contact or overlap each other.

That is, to form the non-blank sections, the abrasive particles of anabrasive particle layer and the abrasive particles of an adjacent onethereof contact or overlap each other in a cutting direction on acutting surface.

In addition, by way of another example of the cutting segment of theinvention, the segment includes at least two regions. At least someportions of the abrasive particle layers in leading and trailing ones ofthe regions are arranged so that a thin blank section of the trailingregion passes along a thick blank section of the leading region duringcutting of the work piece.

By way of further another example of the cutting segment of theinvention, the segment includes at least two regions. At least someportion of the abrasive particle layers in leading and trailing ones ofthe regions are arranged so that a non-blank section of the trailingcutting segment is disposed in a blank section of the leading cuttingsegment during cutting of a work piece.

A cutting tool of the invention includes the cutting segment of theinvention as just described.

According to a preferred embodiment of the cutting tool of theinvention, the cutting tool employs a plurality of cutting segments.Also, at least some portions of the abrasive particle layers in leadingand trailing ones of the cutting segments are arranged so that a thinblank section of the trailing cutting segment passes along a thick blanksection of the leading cutting segment during cutting of the work piece.

According to another preferred embodiment of the cutting tool of theinvention, the cutting tool employs a plurality of cutting segments. Inaddition, at least some portions of the abrasive particle layers inleading and trailing ones of the cutting segments are arranged so that anon-blank section of the trailing cutting segment passes along a blanksection of the leading cutting segment during cutting of the work piece.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 illustrates a conventional diamond tool having a cutting segmentin which diamond particles are randomly dispersed;

FIG. 2 illustrates a conventional cutting segment having diamondparticles evenly dispersed therein, in which (a) is a schematic view ofthe cutting segment and (b) is a cross-sectional view of the cuttingsegment taken along the line A-A;

FIG. 3 is a schematic view illustrating an exemplary cutting segment ofthe invention, in which (a) is a schematic view of a cutting surface and(b) is a cross-sectional view of the cutting segment taken along theline B-B during cutting;

FIG. 4 is a cross-sectional view of the cutting segment seen in frontwhen a work piece is cut via a conventional cutting segment having blanksections uniformly spaced apart from each other;

FIG. 5 is a cross-sectional view of the cutting segment seen in frontwhen a work piece is cut via a cutting segment of the invention;

FIG. 6 is a cross-sectional view of the cutting segment seen in frontwhen a work piece is cut via another cutting segment of the invention;

FIG. 7 is a cross-sectional view of the cutting segment seen in frontwhen a work piece is cut via further another cutting segment of theinvention;

FIG. 8 is a schematic view illustrating another exemplary cuttingsegment of the invention, in which (a) is a schematic view of thecutting segment and (b) is a cross-sectional view of the cutting segmenttaken along the line C-C during cutting;

FIG. 9 is a schematic view illustrating further another exemplarycutting segment of the invention;

FIG. 10 is a schematic view illustrating further another exemplarycutting segment of the invention;

FIG. 11 is a schematic view illustrating further another exemplarycutting segment of the invention;

FIG. 12 is a schematic view illustrating further another exemplarycutting segment of the invention;

FIG. 13 is a schematic view illustrating a preferred embodiment of acutting tool of the invention;

FIG. 14 is a schematic view illustrating another preferred embodiment ofa cutting tool of the invention;

FIG. 15 is a cross-sectional view illustrating the cutting segments seenin front during cutting according to the invention; and

FIG. 16 is a cross-sectional view illustrating the cutting segments of acutting tool seen in front according to the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will now be described indetail with reference to the accompanying drawings.

FIG. 3 illustrates an exemplary cutting segment of the invention.

FIG. 3 (b) is a cross-sectional view of the cutting segment taken alongthe line B-B in FIG. 3 (a) during cutting.

As shown in FIG. 3 (a), the cutting segment 100 of the inventionincludes a plurality of abrasive particle rows 101 having abrasiveparticles 105 arranged in a cutting direction of the cutting segment100. The abrasive particle rows 101 are stacked in a width direction ofthe cutting segment 100 to form a plurality of abrasive particle layers1011 as shown in FIG. 3( b). The abrasive particle layers 1011 aredisposed perpendicular to a cutting direction (in a thickness directionof the cutting segment).

The abrasive layers 1011A have a plurality of blank sections 110therebetween. In the blank sections 110, thin blank sections 110 a andthick blank sections 110 b alternate each other.

In cutting a work piece via the cutting segment 100, as shown in FIG. 3(b), the thin blank sections 110 a are relatively less worn away so thatthe depth h1 of grooves is shallower, thus enhancing a retention powerof adjacent abrasive particles. The thick blank sections 110 b arerelatively more worn away so that the depth h2 of the grooves is deeper.

In this fashion, abrasive particles 105 adjacent to the thin blanksections 110 a are sufficiently retained at least on a side so that theabrasive particles 105 do not fall off easily, thereby lengtheninguseful life of the cutting segment. At the same time, the grooves have agreat depth h2 due to the thick blank sections so that the abrasiveparticles are protruded sufficiently, thereby improving cutting rate ofthe cutting segment.

A major mechanism for increase in cutting rate and useful life will beexplained hereunder according to the invention.

As shown in FIG. 3 (b), virtual big abrasive particles 106 are arrangedon the abrasive particle rows 101 including the thin blank sections 110a. The depth h2 of the grooves caused by the worn-away thick blanksections demonstrates protrusion height between the virtual abrasiveparticles. Given this, the virtual big abrasive particles 106 enhancecutting rate, and prolongs useful life due to the smaller depth h2 ofthe grooves than the size of the virtual big abrasive particles 106.

Preferably, the thick blank sections 110 b each have a thickness TW1 of0.75 to 2 times the average diameter of the abrasive particles. Also,the thin blank sections 110 a each have a thickness TN1 smaller thanthat of the thick blank sections 110 b each within a range greater than0, i.e., the range in which two abrasive particle rows 101 a and 101 bbetween the thin blank sections 110 a do not overlap each other.

Preferably, a thickness ratio TW1/TN1 of the thin blank sections 110 ato the thick blank sections 110 b is 1.5 times or more.

FIGS. 4 to 7 are cross-sectional views illustrating cutting segmentswith a total thickness of T and eight rows of abrasive particlesarranged therein. FIG. 4 illustrates an example of a conventionalcutting segment having blank sections uniformly spaced apart from eachother. FIG. 5 is an exemplary cutting segment having a plurality of thinblank sections and a plurality of thick blank sections alternate witheach other according to the invention. Also, FIG. 6 is another exemplarycutting segment having two blank sections on an outermost side, and thena thick blank section, a thin blank, a thick blank section and two thinblank sections disposed side by side in their order. FIG. 7 is furtheranother exemplary cutting segment 500 having first thin blank sections510 a on both outermost sides, and then first thick blank sections 510b, second thick blank sections 510 c and a second thick blank section510 d disposed side by side in their order.

Thus, the second thick blank section 510 d is disposed in the mostcentral portion of the cutting segment. At this time, the second thinblank sections 510 c are thicker than the first thin blank sections 510a on the outermost sides and thinner than the first thick blank sections510 b. Also, the second thick blank section 510 d is thicker than thefirst thick blank sections 510 b.

As shown in FIG. 4, the conventional cutting segment 200 having theblank sections uniformly spaced apart D2 from each other is worn away sothat its upper surface is rounded, which will be explained hereunder.

An abrasive particle row 201 a in the outermost layer of the cuttingsegment easily falls off since one side thereof is not retained by metalpowder and the blank section 210 on the opposite side is grooved andthus insufficiently retained.

Therefore, an adjacent abrasive particle row 201 b is worn away in arelatively great portion, thus forming a round surface R with respect toa center of the cutting segment.

In case of rounding that occurs as just described, a cutting surface ofthe cutting segment is prone to warping since the cutting tool cannotcut a work piece straightly. This also causes the cutting segment tosustain greater load due to a larger cutting area. The abrasion in alateral portion, if accelerated, removes clearance between a metal coreand the cutting segment, thus rendering the cutting tool useless despiteavailability of the cutting segment.

As shown in FIG. 5, in a cutting segment 300 having a plurality of thinblank sections 310 a and a plurality of thick blank sections 310 balternate with each other, as in the conventional cutting segment 200,an outermost one 301 a of abrasive particle rows 301 is not sufficientlyretained by metal powder on a side. However, at least one side of theoutermost abrasive particle row 301 is sufficiently retained since thethin blank sections 310 a on the opposite sides, which have a smallthickness TN2, are worn away into shallow grooves.

Therefore, in a thickness direction of the cutting segment 300, thecutting segment 300 is worn away in a rectangular shape with anglededges.

As shown in FIG. 6, a cutting segment 400 is disposed with two thinblank sections 410 a on an outermost side, and then a thick blanksection 410 b, a thin blank section 410 a, a thick blank section 410 band two thin blank sections 410 a side by side in their order. In thiscase, the thin blank sections on an outermost side are less abraded thanthe thick blank section in the central portion. This causes the cuttingsegment 300 to be abraded in a concave shape.

Referring to FIG. 7, a cutting segment 500 is disposed with first thinblank sections 510 a in outermost portions, and then first thick blanksections 510 b, second thin blank sections 510 c and a second thickblank section 510 d side by side in their order. Thus, the second thickblank section 510 d is disposed in a central portion. At this time, thesecond thin blank section 510 c is thicker than the first blank sections510 a and thinner than the first thick blank sections 510 b. The secondthick blank section 510 d is much thicker than the first thick blanksections 510 b. In this cutting segment 500, the thickness of the blanksections increases toward a central portion, thereby causing the cuttingsegment 500 to be abraded in a concave shape.

In case where a cutting segment is abraded in a rectangular or concaveshape as in the cutting segments 300 and 400 of the invention, a workpiece is cut straightly, thereby allowing the cutting segment to sustainless cutting load and to be rendered useful till its complete abrasion.

FIG. 8 illustrates an exemplary cutting segment 600 of the inventionincluding a non-blank section 610 a.

As shown in FIG. 8 (a), the cutting segment 600 has a plurality ofnon-blank sections 610 a and a plurality of blank sections 610 balternate with each other in a direction perpendicular to a cuttingdirection of the cutting segment. The non-blank sections 610 a aredisposed between adjacent abrasive particle layers and have no abrasiveparticles arranged therein.

In the non-blank sections 610 a, abrasive particles contact (as innumeral sign 6101 a) or overlap (as in numeral sign 6102 a) each otherwhen seen from a cutting surface of the cutting segment.

In the non-blank sections 610 a, as shown in FIGS. 8 (a) and 8 (b),abrasive particle layers 6011 a and abrasive particle layers 6011 b,which are adjacent each other, are arranged such that an abrasiveparticle row 601 a of an abrasive particle layer 6011 a and an abrasiveparticle row 601 b of an adjacent abrasive particle layer 6011 b contactor overlap each other on a cutting surface.

That is, the non-blank sections 610 a are formed so that abrasiveparticles 605 a of the abrasive particle layer 6011 a and abrasiveparticles 605 b of the adjacent abrasive layer 6011 b contact or overlapin a cutting direction on the cutting surface.

The blank sections 610 b may have uniform or various thickness.

FIGS. 9 to 12 illustrate other exemplary cutting segments of theinvention.

As shown in FIGS. 9 to 12, the cutting segments 150, 160, 170 and 180each include at least two regions of 151,152; 161,162; 171,172 and181,182. Each of the regions includes a plurality of abrasive particlelayers in a direction perpendicular to a cutting direction.

As shown in FIGS. 9 to 10, thin blank sections 110 a and thick blanksections 110 b are disposed between the abrasive particle layers(abrasive particle rows 101).

In FIGS. 9 and 10, at least some portions of the abrasive particlelayers in the leading and trailing regions 151, 152 and 161, 162 arearranged so that a thin blank section of the trailing cutting segmentpasses along a thick blank section of the leading cutting segment duringcutting of the work piece.

Also, as shown in FIGS. 11 to 12, the abrasive particle layers includetherebetween a plurality of blank sections 610 b in which the abrasiveparticles are absent or have a concentration of 70% or less with respectto those in the abrasive particle rows and a plurality of non-blanksections 610 a in which the abrasive particle layers contact or overlapeach other.

In FIG. 11, at least some portions of the abrasive particle layers inthe leading and trailing regions 171 and 172 are arranged so that anon-blank section of the trailing cutting segment is disposed in a blanksection of the leading cutting segment during cutting of a work piece.

The abrasive particle layers are arranged between the adjacent ones ofthe regions so that the abrasive particle layers and blank sections inthe regions are shifted in a thickness direction of the cutting segmentas in FIGS. 9 to 11 or the regions are shifted in a thickness directionof the cutting segment with respect to adjacent regions as in FIGS. 10to 12.

FIG. 13 illustrates a preferred embodiment of a cutting tool of theinvention.

As shown in FIG. 13, a cutting tool 1000 has a metal core 2 fixed with aplurality of cutting segments.

Adjacent ones 100 a and 100 b of the cutting segments are arranged suchthat a thin blank section 110 a of a trailing cutting segment 100 b isdisposed in a thick blank section 110 b of a leading cutting segment 100a during cutting of a work piece.

In cutting the work piece via the cutting tool, the thin blank section110 a of the trailing cutting segment 100 b passes along the thick blanksection 110 b of the leading cutting segment 100 a. That is because theleading cutting segment 100 a and trailing cutting segment 100 b arebonded to the metal core 2 alternately.

Therefore, in an overall sense, this prevents serious abrasion in thethick blank section 110 b, thereby extending useful life of the cuttingsegment.

Also, the thin blank section 110 a is abraded into a shallow groove,thus increasing retention of the abrasive particles and lengtheninguseful life of the cutting tool.

Furthermore, the trailing cutting segment 100 b is capable of cutting aportion which the leading cutting segment 100 a fails to cut duringcutting of the work piece, thereby enhancing cutting rate of the cuttingtool.

FIG. 14 illustrates another exemplary cutting tool of the invention.

As shown in FIG. 14, a cutting tool 2000 has a metal core 2 fixed with aplurality of cutting segments of the invention.

Adjacent ones of the cutting segments 600 a and 600 b are arranged suchthat a non-blank section 610 a of a trailing cutting segment 600 b isdisposed in a position corresponding to a blank section 610 b of aleading cutting segment 600 a.

Also when a work piece is cut via the cutting tool 2000, in an overallsense, the blank section 610 b is prevented from being severely abraded,thus prolonging useful life of the cutting tool as in the cutting tool10000 as just described.

The non-blank section 610 a is abraded into a shallow groove so thatretention of abrasive particles is increased to extend useful life ofthe cutting tool.

Also, the trailing cutting segment 600 b is capable of cutting a portionwhich the leading cutting segment 600 a fails to cut during cutting of awork piece, thereby improving cutting rate of the cutting tool.

MODE FOR THE INVENTION

Preferred embodiments of the present invention will now be described indetail with reference to the accompanying drawings.

Example 1

One saw blade was manufactured according to the invention (Inventiveproduct 1) and two saw blades were manufactured according to the priorart (Conventional products 1 and 2). The inventive and conventional sawblades were used to examine cutting rate and useful life of cuttingsegments in order to cut a granite work piece. The results are shown inTable 1.

Also, abrasion shapes of the cutting segments were observed.

Herein, Inventive product 1 used diamond particles as abrasiveparticles. The segments each had a length L of 40 mm, thickness T of 3.2mm, width W of 10.0 mm, diameter R of 168 mm, and average diamondconcentration of 0.8Conc. The diamond particles used were MBS-955available from D.I corp. of U.S.A., with a particle size of US 40/50mesh and an average diameter of 400

.

FIG. 15 (a) illustrates shapes of cutting segments in Inventive product1 according to this embodiment.

In Inventive product 1, diamond particles were arranged in six rowsparallel to a cutting direction, two thin blank sections were disposedsuccessively at an interval of 0.1 mm in a lateral portion of thecutting segment. The thickness of a thick blank section in a centralportion had a ratio of 1.0 with respect to the average diamond particlesize. The thick blank section had a thickness of 0.4 mm. Also, thethickness ratio between the thin blank section and the thick blanksection was 4.

Conventional product 1 had dimensions equal to those of Inventiveproduct 1, i.e., a length L of 40 mm, thickness T of 3.2 nm, width W of10.0 mm, diameter R of 168 mm and average concentration of 0.8 Conc.,with diamond particles randomly dispersed across the cutting segment.

Conventional product 1 had the diamond particle type and size equal tothose of Inventive product 1.

Conventional product 2 was shaped identical to Conventional 1, also withthe same average concentration and particle size. The diamond particleswere arranged in 6 rows at an equal interval. Accordingly, all blanksections each had a width of 0.16 mm.

The machine used was a bridge sawing machine available from PEDRINIcorp. The cutting tool was sized 14 inches, with a rotational speed of1800 rpm and a cutting speed of 3M per minute.

A work piece was cut with a depth of 30 mm, and a length of 288 m.

Inventive product 1, Conventional product 1 and Conventional product 2used, as a metal powder (bond), a mixture of cobalt, steel and copperhaving an equal composition.

Cutting index shown in Table 1 indicates the amount of power kWhnecessary for cutting a work piece sized 1

. The smaller value thereof means a higher cutting rate. Useful lifeindicates the area

 of the work piece cut when the cutting segment has abrasion of 1 mm.The bigger value thereof means a longer useful life.

TABLE 1 Sample No. Inventive 1 Conventional 1 Conventional 2 Cuttingindex 1.115 (100%) (76.1%) (85.2%) [kWh/

] Useful life 4.341 (100%) (86.3%) (78.3%) [

/mm]

As seen in Table 1, Inventive product 1 exhibits superior useful lifeand cutting rate to Conventional products 1 and 2. Inventive product 1had diamond particles arranged in rows, which were divided into thinblank sections and thick blank sections. Conventional product 1 haddiamond particles randomly dispersed therein. Conventional product 2 haddiamond particles arranged in rows, however at an uniform interval in athickness direction of the cutting segment.

Moreover, in Inventive product 1, the cutting segment was abraded in arectangular shape with a side end portion left intact. On the contrary,Conventional product 1 and 2 were worn away in a round shape.

Example 2

In this Example, cutting segments shaped as in FIGS. 15 (b) to (f) weremanufactured after varying a total number of diamond particle layers(rows on a cutting surface), number and thickness of thin blanksections, ratio of thin blank sections and diamond particle size, numberand thickness of thick blank sections, ratio of thick blank sections anddiamond particle size, thickness ratio of thick blank section and thinblank section, as shown in FIG. 2. Cutting rate and useful life of thecutting segments were observed and the results are shown in Table 3below.

The shape of samples 1 and 2 of Table 2 is depicted in FIG. 15 (b), thatof samples 3, 4 and 5 is depicted in FIG. 15 (c), that of samples 6 and7 is depicted in FIG. 15 (d), and that of sample 9 is depicted in FIG.15 (f).

Cutting rate and useful life of samples shown in Table 3 are comparativevalues when the conventional products having diamond particles randomlydispersed therein are assumed to have a value of 100. At this time, theconventional products had a cutting rate of 315 cm²/min and a usefullife of 18.9 m²/mm.

This Example employed 82-inch large-sized saw blades for machining biggranite raw stone as a board plank. The machine basically featured ahorse power of 50, peripheral speed of 35 m/sec, and cutting depth of 7mm, which were however varied depending on conditions of the cuttingtool. The work piece was granite having an intensity of class 3.

The cutting segments each had a length of 30 mm, thickness of 8.5 mm,height of 13.2 mm, and used, as a metal powder (bond), a mixture ofcobalt, steel, nickel and copper having the same composition.

The cutting segment had a diamond concentration of 0.9 Conc. The diamondparticles used were MBS-960 Ti2 available from D.I. corp., with anaverage particle size of US 40/50 mesh, which is 400

.

The samples of Table 2 had diamond particles arranged in rows includingthe thin blank sections and thick blank sections according to theinvention.

TABLE 2 Thin blank Thick blank Sam- No. section section TR** ple ofGap(TN] Gap[TW] [TW/ No. rows No. (mm) R* No. (mm) R* TN] 1 10 5 0.240.6 4 0.825 2.06 3.44 2 5 0.28 0.7 4 0.775 1.94 2.77 3 12 6 0.12 0.3 50.596 1.49 4.97 4 6 0.26 0.65 5 0.428 1.07 1.65 5 6 0.28 0.68 5 0.4041.01 1.44 6 14 7 0.15 0.38 6 0.31 0.77 2.01 7 7 0.16 0.4 6 0.30 0.741.85 8 9 0.12 0.3 4 0.455 1.14 3.79 9 10 0.16 0.4 3 0.43 1.08 2.71 *R:Ratio with diamond particle size **TR: Thickness ratio of blank sections(TW/TN)

TABLE 3 Sample No. 1 2 3 4 5 6 7 8 9 Cutting 133.6 130.4 125.3 128.9120.4 118.6 111.4 101.5 87.3 rate (%) Useful 114.4 123.6 140.6 135.8128.5 143.7 144.5 147.3 150.1 life (%)

As shown in Table 3, samples 1 to 9 according to the invention exhibitsuperior cutting rate and useful life to conventional products.

In comparison of samples 1 and 2, sample 1 has thick blank sectionsbigger than those of sample 2, thus improving cutting rate butshortening useful life.

Also, samples 3, 4 and 5 have more abrasive particle layers than samples1 and 2, thus exhibiting lower cutting rate but longer useful life. Incomparison of samples 4 and 5, a thickness ratio between blank sectionsof sample 5 is smaller than that between blank sections of sample 4.Accordingly, sample 5 shows inferior cutting and useful life to sample4.

Samples 6, 7 and 8 have 14 abrasive particle layers, thus demonstratingless increase in cutting rate but considerable improvement in usefullife.

In comparison of samples 6 and 7, sample 7 has blank sections withnarrow thickness, thus prolonging useful life over sample 6 but reducingcutting rate.

Samples 8 and 9 have 14 diamond layers arranged therein. Sample 8 has 3thin blank sections successively disposed in a lateral portion of thecutting segment, while sample 9 has 4 thin blank sections successivelydisposed in a lateral portion.

Samples 8 and 9 exhibit superior useful life to the Conventionalproducts, but Sample 9 experiences a sudden decline in cutting ratesince increase in the number of the thin blank section in the lateralportion leads to reduction in cutting rate.

As described above, according to the invention, preferably, the blanksections each have a thickness of 0.75 to 2 times the average diameterof the diamond particles. Preferably, a thickness ratio between thethick blank sections and thin blank sections is 1.5 times or more.Furthermore, preferably, four thin blank sections or more are notsuccessively disposed.

Example 3

24-inch saw blades (samples 10 and 11) were prepared by welding cuttingsegments to an outer peripheral surface of a metal core, in which thecutting segments had thick blank sections and thin blank sections or hadthick blank sections and non-blank sections.

Sample 10 was a cutting tool only comprised of one type of cuttingsegments each having the thick blank sections and thin blank sectionsdisposed therein, out of the cutting segment types according to theinvention.

Sample 11 was a cutting tool having both types of cutting segmentsalternately welded, out of the cutting segment segments according to theinvention. Herein, all the cutting segments included the thick blanksections and non-blank sections, but in the cutting segments, thenon-blank sections of a trailing cutting segment were disposed in thethick blank sections of a leading cutting segment.

FIG. 16 (a) illustrates a cross-section of cutting segments used inSample 10. FIG. 16 (b) illustrates a cross-section of leading andtrailing cutting segments used in Sample 11, in which numeral sign 700 adenotes a cross-section of a leading cutting segment and 700 b is across-section of a trailing cutting segment.

Tables 4 and 5 each indicate a total number of diamond layers (rows on acutting surface), number and thickness of thin blank sections, ratiobetween thin blank sections and diamond particle size, number andthickness of thick blank sections, ratio between thick blank sectionsand diamond particle size, and thickness ratio between the thick blanksections and the thin blank sections regarding samples 10 and 11.

The cutting segments each had a length of 35 mm, thickness of 4.8 mm,height of 10 mm, and used, as a metal powder (bond), a mixture ofcobalt, steel, nickel and copper having the same composition.

The cutting segment had a diamond concentration of 0.9 Conc. The diamondparticles were MBS-970 Ti2 available from D.I. corp., with an averageparticle size of US 40/50 mesh, which is 400

.

The cutting tools (samples 10 and 11) had a horse power of 20 andperipheral speed of 45 m/s. A work piece was cut with a depth of 7 cm toexamine cutting rate and useful life. The work piece was concrete havinga compressive strength of 320 kgf/cm².

Table 6 indicates a comparative value of cutting rate and useful life ofSamples 10 and 11 when a conventional cutting segment having diamondparticles randomly dispersed therein is assumed to have a value of 100.At this time, the conventional product exhibited cutting rate of 700cm²/min and useful life of 5 m²/mm.

TABLE 4 Thin blank Thick blank Sam- No. section section ple of Gap(TN]Gap[TW] No. rows No. (mm) R* No. (mm) R* TR* 10 8 4 0.13 0.325 3 0.360.9 2.77 *R: Ration with diamond particle size **TR: Thickness ratio ofblank sections (TW/TN)

TABLE 5 Thick blank No. Non-blank section Sample Segment of section Gap[TW] No. types rows No. G*(mm) No. (mm) R* 11 Leading 8 4 0.4 3 0.531.325 Trailing 8 4 0.4 4 0.4 1 G*: Gap between rows (mm) R**: Ratio withdiamond particle size

TABLE 6 Sample No. 10 11 Cutting rate (%) 127.5% 118.8% Useful life (%)121.1% 129.2%

As seen in Table 6, samples 10 and 11 of the invention exhibit superiorcutting rate and useful life to the Conventional products.

In comparison of samples 10 and 11, sample 10 experiences furtherimprovement in cutting rate since the cutting segments thereof aredeeply grooved and thus abrasive particles are protruded at a relativelybigger height.

Meanwhile, sample 11 exhibits longer useful life due to shallow grooves.The grooves are shallow because non-blank sections of a trailing cuttingsegment pass along a part of a work piece where thick blank sections ofa leading segment pass.

While the present invention has been shown and described in connectionwith the preferred embodiments, it will be apparent to those skilled inthe art that modifications and variations can be made without departingfrom the spirit and scope of the invention as defined by the appendedclaims.

INDUSTRIAL APPLICABILITY

As described above, the invention provides a cutting segment havingexcellent cutting rate and longer useful life, and a cutting tool.

1. A cutting segment for a cutting tool comprising a plurality ofabrasive particle layers disposed perpendicular to a cutting direction,each of the abrasive particle layers having a plurality of abrasiveparticle rows stacked in a width direction of the cutting segment, eachof the abrasive particle rows having a plurality of abrasive particlesarranged in a line, wherein the abrasive particle layers have aplurality of blank sections therebetween, in which abrasive particlesare absent or have a concentration of 70% or less with respect to thosein the abrasive rows, wherein the blank sections include relativelythick blank sections and relatively thin blank sections, wherein each ofthe thick blank sections has a thickness of 0.75 to 2 times the averagediameter of the abrasive particles, and wherein a thickness ratio of thethin blank sections to the thick blank sections is 1.5 times or more. 2.The cutting segment according to claim 1, wherein the thin blanksections are disposed between the thick blank sections.
 3. The cuttingsegment according to claim 2, wherein the thin blank sections and thethick blank sections alternate each other.
 4. The cutting segmentaccording to claim 2, wherein the number of the thin blank sectionsdisposed between the thick blank sections is less than four.
 5. Thecutting segment according to any one of claims 1 to 4, at least twolayers of the abrasive particle layers are equally concentrated.
 6. Thecutting segment according to claim 5, wherein the abrasive particlelayers in a lateral portion of the cutting segment have a concentrationgreater than those in a central portion of the cutting segment.
 7. Thecutting segment according to any one of claims 1 to 4, wherein theabrasive particle layers in a lateral portion of the cutting segmenthave a concentration greater than those in a central portion of thecutting segment.
 8. The cutting segment according to claim 7, wherein arelatively thinnest one of thick blank sections has a thickness ratio of1.5 times or more with respect to a relatively thickest one of the thinblank sections.
 9. The cutting segment according to claim 8, wherein atleast two layers of the abrasive particle layers are equallyconcentrated.
 10. A cutting segment for a cutting tool comprising atleast two regions, each having a plurality of abrasive particle layersdisposed perpendicular to a cutting direction in each of the regions,each of the abrasive particle layers having a plurality of abrasiveparticle rows stacked in a width direction of the cutting segment, eachof the abrasive particle rows having a plurality of abrasive particlesarranged in a line, wherein the abrasive particles are absent or have aconcentration of 70% or less with respect to those in the abrasive rows,wherein the blank sections include relatively thick blank sections andrelatively thin blank sections, and wherein at least some portions ofthe abrasive particle layers in leading and trailing ones of the regionsare arranged so that a thin blank section of the trailing region passesalong a thick blank section of the leading region during cutting of thework piece.
 11. A cutting tool having a cutting segment as described inclaim
 1. 12. A cutting segment for a cutting tool comprising a pluralityof abrasive particle layers disposed perpendicular to a cuttingdirection, each of the abrasive particle layers having a plurality ofabrasive particle rows stacked in a width direction of the cuttingsegment, each of the abrasive particle rows having a plurality ofabrasive particles arranged in a line, wherein the abrasive particlelayers include therebetween a plurality of blank sections in which theabrasive particles are absent or have a concentration of 70% or lesswith respect to those in the abrasive particle rows, or a plurality ofnon-blank sections in which the abrasive particle layers contact oroverlap each other, wherein the blank sections include thick blanksections, and wherein each of the thick blank sections has a thicknessof 0.75 to 2 times the average diameter of the abrasive particles. 13.The cutting segment according to claim 12, wherein the non-blanksections are disposed between the blank sections.
 14. The cuttingsegment according to claim 13, wherein the non-blank sections and theblank sections alternate with each other.
 15. The cutting segmentaccording to claim 13, wherein the number of the non-blank sectionsdisposed between the blank sections is less than four.
 16. The cuttingsegment according to any one of claims 12 to 15, wherein at least twolayers of the abrasive particle layers are equally concentrated.
 17. Thecutting segment according to claim 12, wherein the abrasive particlelayers in a lateral portion of the cutting segment has a concentrationgreater than those in a central portion of the cutting segment.
 18. Thecutting segment according to any one of claims 12 to 15, wherein theblank sections comprise at least two types having a different thickness.19. A cutting segment for a cutting tool comprising at least tworegions, each of the regions having a plurality of abrasive particlelayers disposed perpendicular to a cutting direction in each of theregions, each of the abrasive particle layers having a plurality ofabrasive particle rows stacked in a width direction of the cuttingsegment, each of the abrasive particle rows having a plurality ofabrasive particles arranged in a line, wherein the abrasive particlelayers include therebetween a plurality of blank sections in which theabrasive particles are absent or have a concentration of 70% or lesswith respect to those in the abrasive particle rows and a plurality ofnon-blank sections in which the abrasive particle layers contact oroverlap each other, and wherein at least some portions of the abrasiveparticle layers in leading and trailing ones of the regions are arrangedso that a non-blank section of the trailing cutting segment is disposedin a blank section of the leading cutting segment during cutting of awork piece.
 20. A cutting tool having the cutting segment for thecutting tool as described in any one of claims 12 to
 15. 21. A cuttingtool comprising: a plurality of cutting segments having abrasiveparticles dispersed therein; and a metal core having the cuttingsegments fixed thereto, wherein the cutting segments comprise a cuttingsegment as described in any one of claims 1 to 4, and wherein at leastsome portions of abrasive particle layers in leading and trailing onesof the cutting segments are arranged so that a thin blank section of thetrailing cutting segment passes along a thick blank section of theleading cutting segment during cutting of the work piece.
 22. A cuttingtool comprising: a plurality of cutting segments having abrasiveparticles dispersed therein; and a metal core having the cuttingsegments fixed thereto, wherein the cutting segments comprise a cuttingsegment as described in any one of claims 12 to 15, and wherein at leastsome portions of abrasive particle layers in leading and trailing onesof the cutting segments, a non-blank section of the trailing cuttingsegment is disposed in a blank section of the leading cutting segmentduring cutting of a work piece.